$pH=2\Rightarrow [H^+]=10^{-2}\Rightarrow n_{H^+}=0,1 mol$$\Rightarrow n_{Cu}=n_{Cl_2}+2n_{O_2}=\frac{n_{HCl}}{2}+\frac{2n_{H^+}}{4}=0,01 mol$
$\Rightarrow \begin{cases}m=0,01.64 gam \\0,01=\frac{0,5.t}{2.96500} \end{cases}\Rightarrow \begin{cases}m=0,64 gam \\ t=3860 s \end{cases}$